1. Field of the Invention
This invention relates to a multiple-use thermal image transfer recording method capable of yielding images by using a thermal image transfer recording medium repeatedly, and more particularly to a thermal image transfer recording method capable of yielding images with the employed thermal image transfer recording medium not creased nor broken while provided with the thermal energy from a line thermal head in the course of the repeated operations of thermal printing.
2. Discussion of Background
Recording apparatus, such as a printer and a facsimile apparatus, using a thermal image transfer recording method, is now widely used. This is because the recording apparatus of this type is relatively small in size and can be produced inexpensively, and the maintenance is simple.
In a conventional thermal image transfer recording medium for use with the thermal image transfer recording apparatus, a single ink layer is merely formed on a support. When such a recording medium is used for printing images, the portions of the ink layer heated by a thermal head are completely transferred to an image receiving sheet at only one-time printing, so that the recording medium can be used only once, and can never be used repeatedly. The conventional recording medium is thus disadvantageous from the viewpoint of running cost.
In order to overcome the above drawback in the prior art, there have been proposed the following methods:
(1) A microporous ink layer containing a thermofusible ink is formed on a support so that the ink can gradually ooze out from the ink layer as disclosed in Japanese Laid-Open Patent Applications 54-68253 and 55-105579;
(2) A porous film is provided on an ink layer formed on a support so that the amount of an ink which oozes out from the ink layer can be controlled as disclosed in Japanese Laid-Open Patent Application 60-40293; and
(3) An adhesive layer is interposed between an ink layer and a support so that an ink in the ink layer can be gradually exfoliated in the form of a thin layer from the ink layer when images are printed as disclosed in Japanese Laid-Open Patent Applications 60-127191 and 60-127192.
However, most of the conventional methods have been developed in such a fashion as to be suitable for use with a serial thermal head in a recording apparatus such as a word processor. Therefore, when those methods are applied to a line thermal head for use in a recording apparatus such as a facsimile apparatus and a bar code printer, the width of the employed thermal image transfer recording medium is necessarily increased and thermal deformation of the thermal image transfer recording medium is inevitable because the time elapsed before the thermal image transfer recording medium is separated from an image-receiving sheet is relatively long after the image transfer recording medium is brought into contact with the image-receiving sheet under application of heat thereto. Because of such thermal deformation of the thermal image transfer recording medium, the recording medium is easily caused to become creased or folded while it is reeled after one-time thermal printing. In addition, a portion of the recording medium to which the thermal energy has been applied is readily stretched. Consequently, the printed image becomes blurred when the above-mentioned thermal image transfer recording medium is repeatedly used and the thermal image transfer recording medium itself is disadvantageously tore at the final stage.